Umm I'm not even sure Garrosh has done anything really really bad to get the whole world turned against him yet. Yes Kalimdor we all know he declared to wipe us out and Ashenvale but don't you think it's not enough yet I mean this isn't just fight for Kalimdor either. It's for all of Azeroth. We're not rolling over to him, I don't know where you got the idea but we are not. I know you got Night Elf pain but lets try and stay reasonable and Garrosh hasn't totally done everything just yet.

Idc about the Horde turning against him. The Alliance should've been planning to wipe him off the face of Azeroth after Cataclysm, but didn't. Gilneas, Theramore, Barrens, Ashenvale, Stonetalon ya, these should've had the Alliance furious already, and they aren't. It's an amazing amount of sheer stupidity and fail on account of Horde loving lore writers that the Alliance needs yet another violent, depraved loss to really get mad at them. One the horde can "sympathise with" (who cares). Alliance can't get mad unless they are basically a corpse, but scratch the Horde and they are hopping pissed, and jumped up about Taurajo -.- (even in lore)

At worst I'd say Garrosh would try and use the Sha again but Cho Lorewalker tries to persuade him but Garrosh kills him in outright cold blood. That could be one reason for Pandaria to fear Garrosh's regime. It may not necessarily piss US off but it will annoy the Pandaren enough to stand up to Garrosh and thus maybe smack some sense in the Horde. I'm sure the plan will be much more grand but it's an idea I'd like to see if it was possible.

I think the "atrocity" was already committed, forcing his own people to get possessed by the Sha, which destroyed them all outright. But I guess that's not enough either.

I could very well see 5.3 being the patch that sets the stage for the finale of Mists of Pandaria with the plans of the Alliance and the Horde rebels coming to light along with the first confrontation with Garrosh that ignites the push to dethrone the fallen warchief. Maybe in the form of scenarios, dungeons or progressive quests (quests taking place in areas we've been before but return to explore new storylines.)

Also possible we could see those battlegrounds that were data-mined from the 5.2 patch content implemented around this time. A patch doesn't need a raid tier in my opinion to constitute as a major content patch. There could be plenty of surprises in store for us come 5.3 and so on.

no dungeons, as Blizzard said they want the previous tiers to be the gearing path. Even the droprates on the first tier in MoP will be increased when 5.2 hits.
It will be just like 5.1, scenario's and dailies to progress the story, i think.

5.1 was great, awesome story telling technique!
I really hope they keep it, also: the amount of dailies was much more manageable, and the constant rewards (in advancing the story instead of MORE DAILIES) made it feel like much less of a chore